The invention relates generally to machines for grinding and reforming the surfaces of railroad track rails. More particularly, the invention relates to an apparatus for grinding the railhead in hard to reach areas such as switch points, like frogs, rail ends, and guard rails. These areas are inaccessible by conventional rail grinding cars and require manual grinding operations.
Railroad track rails are subject to wear by the passage of trains over the rails, and the head surfaces of railroad track rails which are in direct contact with the wheels and wheel flanges of rolling stock tend to wear unevenly. In particular, the cross sectional contour of the head can become misshapen, and depressions in the top surface of the railhead may develop such that the railhead presents a modulating, corrugated surface. Moreover, the railhead may develop burrs or otherwise lose its symmetrical profile. Such defects create undesirable vibration, particularly at high speeds, and also produce high noise levels. Maintenance of smooth running surfaces on railroad track rails is therefore important for reasons of safety, riding comfort, protection of the track, track bed and rolling stock, and noise suppression.
Grinding machines have been developed for maintaining railroad track rails in smooth, properly shaped condition. Such grinding machines generally comprise a plurality of rotatable grinding modules carried by a locomotive or the like in close proximity to the railhead surfaces of the track rail. The grinding modules include rotatable, abrasive grinding stones that can be lowered into a position flush with the rail surface to grind and restore the rail surface to a smooth, desired profile. In particular, on-track grinding trains carrying arrays of heavy grinding stones driven by powerful motors have been used in such grinding operations. An example of such a rail grinding car is disclosed in U.S. Pat. No. 4,583,327, in which there is described a rail grinding car having vertical and horizontal grinding stone units. Horizontal grinding stones are generally annular with a flat, annular face being the grinding surface, whereas vertical grinding stones grind with an outer cylindrical surface of the stone. This grinding car embodies positioning control of an array of vertical grinding stones so that each stone properly engages the rail, and wherein the horizontal grinding stones are individually positionable to provide flexibility in grinding location and concentration on the railheads.
A rail grinding device having active spark control is described in applicants copending U.S. patent application Ser. No. 10/894,198, filed Jul. 19, 2004, which is hereby incorporated herein by reference.
Some grinding machines are specialized to enable them to grind some switch and crossing areas, which are inherently more difficult due to shorter turns, elevation changes and various guardrails. However, some portions of these switch and crossing areas are not capable of being ground by existing automated methods because of the close proximity of frogs, switch rail ends, guardrails, and the like, to the gauge side of the railhead, which prevents conventional grinding units from forming a complete profile. For example, projecting or protruding metal that develops on the field side of switch points and the gauge portion of the stock rail cannot be removed by conventional cup grinders. This projecting metal can become substantial enough that it can hold the point slight open or away from the stock rail. Left uncorrected this can increase the likelihood of a wheel flange selecting the incorrect support rail, which can cause a derail.
Such areas can require a separate procedure, usually involving a self-powered, manually controlled grinder. Commonly, a manual grinder is transported to the area of operation by a separate vehicle, unloaded and carried to the track, where it is attached and operated. The procedure is reversed upon completion of the grinding operation and repeated as necessary as other switches and crossings are encountered. Loading and carrying requires two people, attachment and operation requires one.
Manual, hand-held hydraulically operated grinders are known which are used to grind such areas of the rails, e.g., switch point, frogs, rail ends and the like. These areas would primarily require freehand grinding in which the operator would be put in a bent over position. U.S. Pat. Nos. 3,974,597 and 4,751,794 describe an apparatus for grinding a base of a railroad rail, but not a head of a rail and, and cannot be easily used in tight areas that would otherwise need freehand grinding with a hand-held grinder.
U.S. Pat. No. 6,358,140 describes a grinder support apparatus for supporting a manual grinder, including a conventional hand-held grinder, on a railhead for performing these grinding operations in a safer, more convenient manner. The grinder support apparatus in this patent is described as including a frame having a support wheel adapted to roll on a top surface of the railhead, a handle for a user to move the support wheel and frame along the rail, and a support section for removably connecting the grinder to the frame in a position wherein the grinding wheel of the grinder is held against the surface of the railhead. This device may provide a safer, more convenient manner for individuals to carrying out such grinding operations with manually operated grinders.
However, it would be more desirable to have a rail grinding apparatus which could be used with a rail grinding car to enable the grinding of switch points, frogs, rail ends and like areas of railroad rail tracks which would otherwise require manual grinding, such as by the MC3 crews mentioned previously.
There is a perceived need within the industry for a more efficient method of maintaining hard-to-reach rail profiles than present methods, which include operator controlled grinding with awkward, cumbersome machinery and its associated logistics and personnel requirements.